[Show abstract][Hide abstract] ABSTRACT: Hydroxymethylnitrofurazone (NFOH) is a tripanomicidal prodrug of nitrofurazone (NF), devoid of mutagenic toxicity. The purpose of this work was to study the chemical conversion of NFOH into NF in sodium acetate buffer pH 1.2, 7.4 and in human plasma and to determine pre-clinical pharmacokinetic parameters in rats. At pH 1.2, the NFOH was totally transformed into NF, the parent drug, after 48 hours, while at pH 7,4, after the same period, the hydrolysis was 20%. In human plasma, 50% of NFOH was hydrolyzed after 24 hours. In the investigation of kinetic disposition the serum concentration versus time curve were used to calculate the pharmacokinetic parameters, after a single-dose regimen. NFOH showed Tmax in 1 hour, suggesting faster absorption when compared with administered NF (4 hours). The most important result observed was the distribution volume (Vd) through the tissues of NFOH that showed a rate that is 20 fold higher (337.5 L/kg) than NF (17.64 L/kg) and the concentration of NF obtained by in vivo metabolism of NFOH showed about four times lower (Cmax = 0.83 μg/mL, AUC 0-12 = 5.683 μg/mL.h) than observed for administered NF (Cmax = 2.78 μg/mL, AUC 0-12 = 54,49 μg/mL.h). These findings can explain the superior activity and lower toxicity of the prodrug NFOH in relation to its parent drug and confirm NFOH as a promising antichagas drug candidate.
Antimicrobial Agents and Chemotherapy 09/2013; · 4.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This report describes the development and validation of a simple, rapid, and efficient method in which solid-phase extraction followed by analysis in a gas chromatograph equipped with an electron capture detector (SPE-GC-ECD) is used for the simultaneous determination of dicofol, dieldrin, endosulfan, and permethrin in rat adipose tissue. This study targeted pesticides for which controversies exist regarding the harm that they may cause to humans, such as endocrine disruption or cancer, and that have also been found in recent years in vegetables consumed by the Brazilian population. The analytical procedure was optimised for SPE extraction and for GC-ECD conditions. The optimised method includes the extraction of the samples with n-hexane followed by an SPE procedure in which deactivated neutral alumina cartridges are used as the sorbent and a mixture of n-hexane:dichloromethane is used for elution. Recovery studies with spiked samples were used to evaluate the method's efficiency. Mean recoveries ranged from 75% to 119% with relative standard deviations (RSD)<19%. Quantification limits (LOQs) were 0.05mgkg(-1) for dieldrin and endosulfan and 0.5mgkg(-1) for dicofol and permethrin. The matrix effect was pronounced for all of the pesticides studied and ranged from 26% to 49%. In comparison to other related methods, this method requires less time and solvent and allows for rapid isolation of the target analytes with high selectivity. This method therefore allows for the screening of numerous samples and can also be used for routine analyses.
[Show abstract][Hide abstract] ABSTRACT: This study reports the influence of sugar cane vinasse on the persistence, sorption and leaching potential of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), hexazinone (3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4-dione) and tebuthiuron (1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea) in both a clay and sandy soil from a tropical area of Brazil. The experiments were conducted out under controlled laboratory conditions. The addition of sugarcane vinasse to soil influenced the persistence and sorption of the herbicides in both the studied clay and sandy soils, with a considerable decrease in the diuron DT₅₀ values in clay soil. The Ground Water Ubiquity Score (GUS) Index classifies the herbicides as leachers in both soils and treatments, with the exception of diuron, which is classified as a non-leacher in clay soil-vinasse and as a transient herbicide in sandy soil. These results suggest that special attention should be given to areas such as those where the sandy soil was collected in this study, which is a recharge area of the Guarani Aquifer and is likely to experience groundwater contamination due to the high leaching potential of the applied pesticides.
Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 11/2012; 47(10):949-58. · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study provides data on the presence of the pesticides atrazine, chlorpyrifos, α-endosulfan, β-endosulfan, flutriafol, malathion and metolachlor in water matrices in urban and rural areas of Campo Verde and Lucas do Rio Verde Cities, Mato Grosso State, Brazil. Surface, rain, and groundwater samples were collected in the rainy and dry seasons during 2007 and 2008 in these important grain-producing areas. The findings revealed a higher diversity of compounds and frequency of detection in the rain water than in surface and groundwater samples. Concentrations of atrazine, endosulfan and malathion above those permitted by Brazilian regulations were found in some surface and groundwater samples, and the degradation products DIA (deisopropylatrazine) and endosulfan sulfate, rather than their parental compounds, were found at higher levels in some samples. Our findings show the vulnerability of water systems in these areas and point to the risk of pesticide contamination in important headwater streams.
Journal of the Brazilian Chemical Society 08/2012; 23(8):1476-1487. · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Rapadura is the commercial name for unrefined dehydrated sugarcane juice. Rapadura is produced in 25 countries, for an estimated total of 13 million tons per year. It is considered a basic food for the School Meals Program (PNAE) in Brazil, which serves 37 million meals to schoolchildren each day. During the production of rapadura, carcinogenic compounds including polycyclic aromatic hydrocarbons (PAHs) may enter this food. A simple and rapid method was optimized and validated for the determination of 16 PAHs in commercial rapadura by high performance liquid chromatography with fluorescence detection (HPLC-FL). PAHs were measured in 80% of the samples (n=21) at levels ranging from 0.07 to 4.03μgkg−1. These data reveal a wide variability in PAH concentrations in the samples, indicated that sugar-cane burning and/or production are important for introduction of these contaminants into rapadura. In Brazil, there are no maximum acceptable PAH levels in this food.
Journal of Food Composition and Analysis - J FOOD COMPOS ANAL. 01/2011; 24(3):346-350.
[Show abstract][Hide abstract] ABSTRACT: Samples of soil, water and sediment were collected and analyzed in order to evaluate chromium contamination due to deposition of tannery residues onto soils under different management regimes. The results showed that soils used for sugar cane cultivation were not adversely impacted. However, in the case of mango plantations, variable concentrations of chromium were measured in the soil profile, with 22.2% of values being higher than permitted legal limits, and 38.9% being at levels requiring remediation. Concentrations of bioavailable chromium were lower than the detection limit of the method (0.01 mg of chromium kg-1 of soil), indicating that all of the chromium present in the samples was either complexed or in an insoluble form. Chromium concentrations measured in samples of water and sediments were indicative of low mobility of the metal in soils. The main cause of differences found between soil samples obtained from different cultivations was the type of soil management.
Química Nova 12/2008; 32(7):1693-1697. · 0.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Residues of the herbicides simazine, metribuzin, metolachlor, trifluralin, atrazine, and two metabolites of atrazine, deisopropylatrazine (DIA) and deethylatrazine (DEA), are surveyed in the surface and groundwater of the Primavera do Leste region, Mato Grosso, Brazil during September and December 1998 and April 1999. Different water source sampling stations of groundwater (irrigation water well, drinking water well, and water hole) and surface water (dam and river) are set up based on agricultural land use. A solid-phase extraction procedure followed by gas chromatography-nitrogen-phosphorus detection is used for the determination of these compounds. All compounds are detected at least once in water samples. A temporal trend of pesticide contamination is observed, with the highest contamination frequency occurring in December during the main application season. Metribuzin shows the highest individual detection frequencies throughout the monitoring period, followed by metolachlor, simazine, and DEA. The maximum mean concentrations of pesticides in this study are in the range from 0.14 to 1.7 microg/L. We deduct that the contamination of water resources is predominantly caused by non-point pollution of pesticides used in intensive cash-crop cultures of the Cerrado area. Therefore, a continuous monitoring of pesticide concentrations in water resources of this tropical region is necessary to detect the longer term contamination trends and developing health risks.
Journal of chromatographic science 09/2008; 46(7):585-90. · 0.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Many classes of pesticides have been used to control and/or to eliminate pests, mainly in agricultural areas. Although decreases in food production have been avoided through pesticide use to combat pests that damage cultivated plants, it is important to consider that their continuous use can result in risks to human health and the environment.This study describes pesticide uses and their evaluation using environmental indicators, which could be used as a planning and policy tool by governmental agencies. = Diversas classes de pesticidas têm sido amplamente utilizadas no controle e/ou combate às pragas, principalmente em áreas agrícolas. Embora a redução da produção de alimentos seja evitada pelo uso de pesticidas, responsáveis pelo combate de organismos danosos às plantas cultivadas, é importante considerar que a utilização contínua dos mesmos pode resultar em riscos à saúde humana e ao meio ambiente. Este trabalho discute os riscos associados ao uso de pesticidas e sua avaliação por indicadores ambientais, que podem servir de base para o planejamento e implantação de políticas públicas por órgãos governamentais competentes.
[Show abstract][Hide abstract] ABSTRACT: Aiming to evaluate the contamination of groundwater by pesticides in cotton growing areas, an SPE-based method (styrene-divinylbenzene copolymer - SDVB) was developed for the simultaneous determination of twelve pesticides in water by HPLC/DAD. The method was validated and average recoveries ranged from 73 to 113%, with a relative standard deviation of 2 to 16%. Detection limits ranged from 0.06 to 0.57 µg L-1. The method was applied to groundwater samples (110) from cotton fields located in "Primavera do Leste", Mato Grosso state, Brazil. Eight pesticides (acetamiprid, aldicarb, carbendazin, carbofuran, diuron, imidacloprid, methomyl and teflubenzuron) were found in the analyzed groundwater samples and 18% of them contained at least one of the pesticides (with concentrations ranging from 0.78 to 68.79 µg L-1). In some cases, detected concentrations exceeded the target levels set by the European Union. These findings confirm the vulnerability of shallow groundwater in the aforementioned areas to pesticide contamination.
Journal of the Brazilian Chemical Society 01/2008; 19(6). · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This work reports on the development and validation of a small-scale and efficient SPE-HPLC-UV method for the simultaneous determination of the most used herbicides (diuron, hexazinone, and tebuthiuron) applied to soil and soil treated with sugar cane vinasse (soil-vinasse) in areas where sugar cane crops are grown in the state of São Paulo, Brazil. The analytical procedure was optimized for solvent extraction and HPLC-UV conditions. Extraction and clean-up were combined in a single step employing solid-phase extraction, avoiding sophisticated techniques, organic–solvent–water mixtures and consequently a longer concentration step. Recovery studies with soil and soil-vinasse samples spiked at two herbicides levels (around 0.25 and 2.0 mg kg−1) and sample stability (sample frozen for 20 days before analysis) were applied as parameters to control the efficiency of the method. Good accuracy and precision were achieved with average recoveries ranging from 78% to 120% and relative standard deviations less than 10% throughout the whole recovery test. The method's limit of detection ranged between 0.025 and 0.050 mg kg−1 for diuron, hexazinone, and tebuthiuron in soil and soil-vinasse. The feasibility of this method was applied to determine the herbicide half-lives (t1/2) in soil and soil-vinasse in a laboratory study. Sugar cane vinasse added to soil increased the degradation of diuron and tebuthiuron (p < 0.05), reducing the t1/2 from 80 to 7 days and 128 to 73 days, respectively. This method is presented as an alternative which could be applied to assess herbicide behavior in soil in order to prevent water contamination and to contribute to establish pesticide limits in soil.
[Show abstract][Hide abstract] ABSTRACT: Persistent organic pollutants (POPs), organochlorine pesticides and polychlorinated biphenyls (PCBs), listed as per the Stockholm Convention (alpha -HCH, beta -HCH, gamma -HCH, p,p'-DDT, o,p'-DDT, p,p'-DDD, p,p'-DDE, aldrin, endrin, dieldrin, PCBs 28, 52, 118, 138, 153, and 180), were analyzed in municipal solid waste (MSW) compost samples from three different Brazilian composting plants located in three São Paulo State cities: Araras, Araraquara and São Paulo (Vila Leopoldinha). Quantitative and qualitative analyses were carried out using gas chromatography electron capture detection (GC-ECD) and gas chromatography mass spectrometry (GC-MS) (Ion Trap, electron impact ionization), respectively. The samples were analyzed in triplicate and the target POPs were not detected by GC-ECD. Twelve pollutants were identified in two samples when qualitative analysis (GC-MS) was used (beta -HCH, gamma -HCH, p,p'-DDT, o,p'-DDT, p,p'-DDD, and p,p'-DDE, PCBs 28, 118, 138, 153 and 180). The composting process has advantages such as urban solid waste reduction and landfill life-span increase, however the MSW compost quality, which can be utilized for agricultural purposes, should be evaluated and be controlled. This kind of study is the first step in making available information to answer questions regarding MSW compost for sustainable agricultural use, such as the pollutants accumulation in soil and in groundwater, and plants uptake.
Journal of Environmental Science and Health Part B 09/2007; 42(6):697-705. · 1.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A method is optimized to determine benomyl (as carbendazim derivative) in shiitake mushrooms. It is based on the extraction of the fungicide with an ethyl acetate-hexane mixture and a further analysis of the extract by high-performance liquid chromatography-UV. Mean recoveries are evaluated and range from 76% to 86% with relative standard deviation between 1.1% and 5.8%. The limit of quantitation (0.5 mg/Kg) is lower than the maximum residue level established by European legislation. The method is successfully applied to the analysis of shiitake mushrooms cultivated on eucalyptus logs treated with Benlate 500 (benomyl as active ingredient) under natural environmental conditions.
Journal of chromatographic science 08/2007; 45(6):340-4. · 0.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A discussion about groundwater contamination is presented in this work. Contamination by agricultural activity, more specifically by pesticides is emphasized. Indirect and direct estimates could be used to predict pesticide behavior in soil, and consequently, to evaluate the potential of groundwater contamination. These results could be applied to advise about the possibility of groundwater contamination by pesticides, and to provide subsidies for making decisions more quickly and efficiently.
Química Nova 06/2007; 30(3):688-694. · 0.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A simple and rapid method was developed for the determination of amfepramone hydrochloride, fenprorex, and diazepam in capsules using high performance liquid chromatography (HPLC) with UV detection. This procedure provided conditions for the separation of the active ingredient from the complex matrices of the dosage forms by extraction in methanol. Isocratic reversed phase chromatography was performed using acetonitrile, methanol, and aqueous 0,1% ammonium carbonate (50:10:40) as a mobile phase, LiChrospher 100 RP 18 column (125 × 5 mm id, 5μm), a column temperature of 25 ± 1°C and detection at 230 nm.The calibration curves were linear over a wide concentration range (20–2000 μg.mL to amfepramone hydrochloride, 8–800 μg.mL to fenproporex, and 4–200 μg.mL to diazepam) and good analytical recovery (87.1 to 107.8%) was obtained. The method is accurate and precise, as well as having advantages such as simplicity and short duration of analysis. Twenty samples of pharmaceutical preparations labelled as “natural” products were analysed. Anorectics and diazepam, were detected in 40% of the samples.
J. LIQ. CHROM. & REL. TECHNOL. 02/2007; 23(7)(1109–1118 (2000)):1109-1118.
[Show abstract][Hide abstract] ABSTRACT: Biosensors for determination of carbamates in vegetables based on five different cholinesterase as biorecognition elements and a screen-printed electrode system as an amperometric transducer were developed. Measurements were simply performed by dropping solutions (either sample or substrate) directly on the biosensor. The response of biosensors to selected carbamates (aldicarb, carbaryl, carbofuran, methomyl and propoxur) was characterized. The performance was evaluated on extracts of potatoes and carrots, the results from the AChE biosensor and a standard HPLC procedure were compared. Finally, the biosensor was used for the direct analysis of vegetable juices without any pretreatment steps. In this case, 10 μg/L levels of added carbofuran and propoxur were reliably identified. The whole procedure takes less than 20 min including 10 min incubation with samples. The concentrations of carbamates determined with biosensor agreed well for carbofuran. Lower response was observed for propoxur.
[Show abstract][Hide abstract] ABSTRACT: An alternative method using liquid chromatography with UV detection for the determination of prochloraz as 2,4,6-trichlorophenol in mango, papaya and orange is described. Ethyl acetate, acetone and dichloromethane were tested for extraction of prochloraz from the fruits. After extraction the residue of prochloraz was derivatized with pyridine hydrochloride. The analysis was carried out using liquid chromatography with UV detection and gas chromatography with electron-capture detection. Average recoveries of prochloraz from spiked fruits (0.1 and 0.2 mg kg-1) ranged from 80% to 94% with relative standard deviations between 5.6% and 12.6% (n=8). Detection and quantification limits were 0.05 and 0.1 mg kg-1, respectively. The LC-UV method was applied to mango and papaya samples submitted to dip treatment with a prochloraz formulation under laboratory conditions. In addition, fruit samples obtained from local markets were analysed.
Journal of the Brazilian Chemical Society 01/2005; 16(2). · 1.28 Impact Factor